Wang Chunyang, Zhang Rui, Siu Carrie, Ge Mingyuan, Kisslinger Kim, Shin Youngho, Xin Huolin L
Department of Physics and Astronomy, University of California, Irvine, California 92697, United States.
Materials Engineering Research Facility, Applied Materials Division, Argonne National Laboratory, Lemont, Illinois 60439, United States.
Nano Lett. 2021 Nov 24;21(22):9797-9804. doi: 10.1021/acs.nanolett.1c03852. Epub 2021 Nov 9.
The pressing demand in electrical vehicle (EV) markets for high-energy-density lithium-ion batteries (LIBs) requires further increasing the Ni content in high-Ni and low-Co cathodes. However, the commercialization of high-Ni cathodes is hindered by their intrinsic chemomechanical instabilities and fast capacity fade. The emerging single-crystalline strategy offers a promising solution, yet the operation and degradation mechanism of single-crystalline cathodes remain elusive, especially in the extremely challenging ultrahigh-Ni (Ni > 90%) regime whereby the phase transformation, oxygen loss, and mechanical instability are exacerbated with increased Ni content. Herein, we decipher the atomic-scale stabilization mechanism controlling the enhanced cycling performance of an ultrahigh-Ni single-crystalline cathode. We find that the charge/discharge inhomogeneity, the intergranular cracking, and oxygen-loss-related phase degradations that are prominent in ultrahigh-Ni polycrystalline cathodes are considerably suppressed in their single-crystalline counterparts, leading to improved chemomechanical and cycling stabilities of the single-crystalline cathodes. Our work offers important guidance for designing next-generation single-crystalline cathodes for high-capacity, long-life LIBs.
电动汽车（EV）市场对高能量密度锂离子电池（LIB）的迫切需求要求进一步提高高镍低钴阴极中的镍含量。然而，高镍阴极的商业化受到其固有的化学机械不稳定性和快速容量衰减的阻碍。新兴的单晶策略提供了一个有前景的解决方案，但单晶阴极的运行和降解机制仍然难以捉摸，特别是在极具挑战性的超高镍（Ni>90%）体系中，随着镍含量的增加，相变、氧损失和机械不稳定性会加剧。在此，我们破译了控制超高镍单晶阴极增强循环性能的原子尺度稳定机制。我们发现，超高镍多晶阴极中突出的充放电不均匀性、晶间开裂和与氧损失相关的相降解在其单晶对应物中得到了显著抑制，从而提高了单晶阴极的化学机械稳定性和循环稳定性。我们的工作为设计用于高容量、长寿命锂离子电池的下一代单晶阴极提供了重要指导。
